heat pump system question

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Is the condenser outside supposed to run the whole time the system is on? I've never seen mine turn on it's always the neighbors. I've always lived in houses with a gas furnace, so I'm not familiar with how an electric one works. I did read somewhere that instead of the condenser removing heat like in the summer that it reverses and puts heat back in. At first I thought the neighbor had the air conditioner on when it was like 35 degrees outside. lol
 
It shouldn't run all the time, but yes, that is the method. It "moves" heat through the refrigerant into the house in the winter, and out of the house in the summer. As long as the outdoor temp is above the min temp of the system (generally 5*F, more or less), the heat pump can typically be more energy-efficient than a gas or electric furnace. It's all about the COP (coefficient of performance) at the outside temps that should drive the decision on what heat source to use.
 
I would hesitate to say a heat pump is more efficient(cost effective really) than a natural gas furnace.

Now vs propane.. way better.

In my experience heat pump can easily be 3:1 or more efficient than electric heating.

Heat pump is very nice for warmer climates.

Not so nice if you have to turn on aux. oil or electric heat.
 
I guess it's a heat pump system. I have central ac, just thought it was weird at first when the outside ac units were running in the winter. I never really researched it.
 
At one time , dual fuel HP's were available that used a gas fires furnace as emergency / auxiliary heat .

This might be the best of both worlds if you have gas available .

Not sure of the cost of propane vs the cost of electric resistance heat ?

If you live in a climate where it rarely gets below , say , 25F , a HP would be worth considering .
 
Originally Posted By: motor_oil_madman
Is the condenser outside supposed to run the whole time the system is on? I've never seen mine turn on it's always the neighbors. I've always lived in houses with a gas furnace, so I'm not familiar with how an electric one works. I did read somewhere that instead of the condenser removing heat like in the summer that it reverses and puts heat back in. At first I thought the neighbor had the air conditioner on when it was like 35 degrees outside. lol

It depends on your system. I have a heatpump with an electric heat strip in the air handler unit so the condenser does NOT turn on for heat. My previous home did not have the heat strip so the condenser did turn on for heat.

The reason why the electric strip is better is at or below freezing the fins in the outside unit can develop frost and the unit has to go through a defrost cycle before it can function and produce heat. The tech who installed my current system said the one or two times a winter here in Phoenix when it dips below freezing they get swamped with calls from customers who complain they are not getting heat. This is why the systems they install now all have the heat strip.
 
The one thing I can't figure out is how to switch it over to a.c. mode. If that's the case I want to run the air conditioner periodically to keep everything lubed up.
 
I remember times where I was younger and my dad turned the a.c. on for the first time in 6 months and it sounded like the fan motor was seized up for a moment outside.
 
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You do not want to run as in the winter unless its above 70*. Heat pumps are ok to run in heating that's what their made for. In cooling the pressures that they run in cooling will trash the compressor unless the unit is set up for low ambient temps. On your thermostat it will have a heat, cool and emergency heat setting if it's a heat pump. Look at you tube videos under heat pump operation.
 
Originally Posted By: azjake
Originally Posted By: motor_oil_madman
Is the condenser outside supposed to run the whole time the system is on? I've never seen mine turn on it's always the neighbors. I've always lived in houses with a gas furnace, so I'm not familiar with how an electric one works. I did read somewhere that instead of the condenser removing heat like in the summer that it reverses and puts heat back in. At first I thought the neighbor had the air conditioner on when it was like 35 degrees outside. lol

It depends on your system. I have a heatpump with an electric heat strip in the air handler unit so the condenser does NOT turn on for heat. My previous home did not have the heat strip so the condenser did turn on for heat.

The reason why the electric strip is better is at or below freezing the fins in the outside unit can develop frost and the unit has to go through a defrost cycle before it can function and produce heat. The tech who installed my current system said the one or two times a winter here in Phoenix when it dips below freezing they get swamped with calls from customers who complain they are not getting heat. This is why the systems they install now all have the heat strip.


The heat pumps go backwards in defrost mode (back to being an A/C) to deal with the frost. They use the electric coils to warm the air in that mode so you do not get cold air into the house during defrost.
 
It all depends on how its set up. If you have natural gas it is unlikely IMHO a heat pump is worth it since natural gas is cheaper than dirt right now. A heat pump may be more efficient than a natural gas furnace at warmer temps, say above 40, but not necessarily cheaper.

Some heat pumps are set up to lock out under a certain temperature.

Now we Have either electric or propane as our heating choices.

We have a higher efficiency heat pump, It makes sense to run ours to -10F due to the efficiency of the unit, and our use of costly electric heat strips as backup.

So if its over -10f and the thermostat is calling for heat, the outside unit is running. When the unit goes into defrost mode, the outside units fan shuts off and the compressor continues to run. (basically it reverts back to being an air conditioning unit, it will remove heat from the house to warm and defrost the outside coils).

On our unit it will not defrost when the outside temperature is over 50F because it is not needed.

Now the heat strips will kick on when the unit goes into defrost (otherwise you would have cold air blowing out of your registers) OR when the heat pump cannot keep up due to the outside temperature being lower. This is called the balance point.

Our balance point is roughly 25F. Anything lower than that supplemental heat is required. It Depends on the wind, if we have basement registers open ect.

Now you can put your thermostat in "emergency heat" mode. Basically this turns off the outside unit, no matter the conditions, and will strictly run your heat strips in the furnace, or propane/gas burner. This is intended if you have an issue with your outside unit.


Heat from a heat pump is very efficient. You are not burning any fuel to create heat when just the heat pump is running, you are just paying to move the heat indoors.

Like I tell my wife, our heat is free, we just have to pay to get it in the house.
 
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Originally Posted By: motor_oil_madman
The one thing I can't figure out is how to switch it over to a.c. mode. If that's the case I want to run the air conditioner periodically to keep everything lubed up.


Unlike automotive AC systems, home AC units should not be run in winter and there is nothing to lube up. The risk to zero reword is quite great.
Heat pumps have heated compressors, that's why they can operate in winter.
 
I will add that since I do not want the heat strips to kick on unless absolutely necessary, and I dont care if we get cold air during defrost mode, that I have made changes to the control scheme of the heat strips.

Not many people would do this, But I am a special kind as my wife tells me...

But she admits it has saved us alot. We ran one winter on the factory control scheme, and after my modifications, it saved us rough 25%, at the slight expense of comfort, but not really that noticeable.
 
Yes, a heatpump will run loonger as temps drop.

The compressor will actually use FEWER amps at lower temps - most don't realize this.

Inside the compressor, all the moving parts are bathed in oil, so there is technically no additional wear for long run times - fan motors however will eventually wear with long run times . . .
 
Originally Posted By: oldoak2000
Yes, a heatpump will run loonger as temps drop.

The compressor will actually use FEWER amps at lower temps - most don't realize this.

Inside the compressor, all the moving parts are bathed in oil, so there is technically no additional wear for long run times - fan motors however will eventually wear with long run times . . .


Yes, good point!

At 0 degrees out heatpump uses a little under 3 kwh an hour. At 55 degrees that goes up to around 4.5

The compressor does not have to work as hard as the temps cool down because your line pressure also drops.

Ours has run for weeks straight in the winter with no ill effects. Its almost 10 years old.

I LOVE our heatpump.

I was a slave to the woodstove one winter here. Never again.

I took the woodstove off our homeowners and the amount saved on insurance nearly pays for the worst month of heating costs.
 
We just got a heat pump with electric coil backup, and in-line humidifier installed this winter and we love it. Coming from a 30 year old oil furnace the difference is ridiculous; quiet, consistent, cleaner (had soot and smell issues with the oil), and more expensive these first two months, but that's to be expected in the middle of winter.

With regards to how often they are running, it depends on the settings just like any other furnace. If your thermostat is set high, it'll be running more often. I have noticed it kicks on more often than the oil furnace did, but the temperature is also much more comfortable rather than constantly going up and down like it did before.
 
We have a heat pump piggybacked on a gas furnace, which seems like a good way to go here. All the contractors swear that it is cheaper to heat with the heat pump. The system automatically shifts to the gas furnace below 30F. Funny but my wife will tolerate my setting the thermostat at 69F with warm gas heat coming out of the vents but not the heat pump.
 
Originally Posted By: Indydriver
We have a heat pump piggybacked on a gas furnace, which seems like a good way to go here. All the contractors swear that it is cheaper to heat with the heat pump. The system automatically shifts to the gas furnace below 30°F. Funny but my wife will tolerate my setting the thermostat at 69F with warm gas heat coming out of the vents but not the heat pump.


The Heat pump heat is a "cool" heat. When its 0°F outside you typically get a 10° degree rise at the registers. So if its 70°F in the house it blows out at 80°F from the registers and that of course feels "cool".

I will say it helps keep the house more consistent vs. the on off cycling of a one stage gas furnace.

I will say after a day working outside in the extreme cold, the warmth of gas heat is nice.
If I start missing this I kick on the 20kw heat strips along with the heat pump and it bumps the register temp to 110°F or so. It feels so good for a bit.
 
We have a heat pump and propane. The heat pump work down to 29 degrees at which point the furnace takes over. Works really well. We keep the temp inside at 69 degrees. My electric bill has been running around $140, a tank of propane which was filled in October will need to be refilled at the end of February at the cost of about $600. Now that also runs my stove which is also propane. That averages me about $290 a month in energy costs between gas and electric. People around me with total electric are getting $5-600 dollar a month bills with similar size homes.
 
Its hard to compare various heat pumps and hybrid systems. The new heat pumps are significantly better than they were 10 years ago. Not sure how many hybrid systems are being installed these days. Most new heat pumps have electric coils.
 
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